The union said the strike would last for three days and involve around 10,000 workers.

Ojobo said union officials would hold talks with the labour minister in the capital, Abuja, later on Wednesday. “If the issues at stake are resolved and a communique signed, the strike would be called off,” he said.

He also said workers had gone on strike at seven crude oil flow stations in and around Oleh, a town in Delta state, which is in the Niger Delta.

“Seven flow stations belonging to NPDC were shut by the workers and they are still shut now,” Ojobo said. He also said the workers, who are employed by contractors, say they have not been paid. The flow stations were shut on Tuesday.

The Labour ministry spokesman was not immediately available to comment.

Nigeria has been hit hard by a slump in crude oil prices in the past two years, which helped to push the country into recession. A wave of militant attacks in the southern Niger Delta oil hub throughout 2016 has hampered production.

Ndu Ughamadu, a spokesman for Nigerian Petroleum Development Company (NPDC), a subsidiary of the state-run oil company NNPC, said checks were being made to establish whether the Niger Delta flow stations had been affected.

Last week, NUPENG held a strike at Total’s fuel depots in a protest over sackings, but it was suspended after one day after an agreement was reached. No details have emerged about the deal.